Screw driver



M y 1929. w. s. THOMSON 1,712,434

SCREW DRIVER Filed April 14, 1926 Patented May 14, 1929.,

UNITED STATES PATENT OFFICE.

WILLIAM STRATON THOMSON, OF I LANTSVILLE, CONNECTICUT, ASSIGNOR TO THE TOBRIN TOOL COMPANY, OF PLANTSVILLE,' CONNECTICUT, A CORPORATION.

SCREW DRIVER.

Application filed April 14,

My invention relates to improvements in screw-drivers, of the form having an elongated shank that is entered through a ferrule into one end of a handle of Wood and in which the said handle is made of a single piece of Wood that is shaped so as to provide adjacent the outer end of relatively enlarged ball structure that is adapted under conditions of use to rest in the palm of the hand of the operator, one side thereof being nested agalnst the palm and the other side being engaged by the fingers in eifecting a grip, and the object of my improvement is to provide for the ball structure mentioned an oval or elliptical form of cross-section, so that the opposite faces referred to as being engaged respectively by the palm and the fingers Wlll be relatively flat so as to enhance the grip, and, also, to further enhance such holding effect by providing forsuch faces some form of broken or rough surface, such as maybe obtained by the use of a plurality of toothlike projections or the like.

In the accompanying drawing Figure 1 is a side elevation of my improved screw-driver.

Figure 2 is a plan view of the handle portion of the same and on an enlarged scale.

Figure 3 is an end elevation of the same.

Figure 4 is a sectional view on the line 44 of Fig. 2.

.Iiigure 5 is a plan View, corresponding to liig. 2, of a modified form for the rough surface feature of the handle.

Figure 6 is a sectional view on the line 6-43 of Fig. 5.

My invention relates to improvements in screw-drivers of the form having the blade structure 10 that terminates in the bit 11 at one end and at the other end the relatively enlarged ball-like structure 12 that constitutes the outer end portion of the handle 13.

Extending inwardly from the blade structure 10 is the elongated shank 14 that is entered into the inner end portion of the said handle 13.

At the junction of the shank 14 and the handle 13 there is a ferrule that, as shown, may be appreciably elongated. 11 pin 17 is entered through one Wall of the ferrule 16 1926. Serial No. 101,954...

and through material of the handle 13 and Some form of ball structure as part of the handle of a screw-driver is common.

In the present instance the shape issuch as may be briefly described as providing relatlvely flattened top and bottom faces 18 so that the form of cross-section is oval or elliptical for both the longitudinal section and the transverse section.

In their angular relation to the axis said opposite faces 18 correspond to opposite flat faces 19 of the blade 10.

While the opposite faces 18 are referred to as being relatively flat, they are not actually fiat but are appreciably curved and continuously curved from end to end, such curvature being, however, appreciably less than for the intervening edge faces 20.

The provision of the relatively flattened faces 18 serves to enhance the holding effect in the hands of the operator as in gripping the handle one face Will rest in the palm of the hand and the other Will be engaged by the fingers.

In order to further enhance the hold or grip, the faces 18 are finished in some manner so as to provide a broken surface. One Way of doing this is to provide a set of teeth or projections 21 that are separated one from the other by intervening depressions or valleys 22.

As shown, the teeth 21 are arranged in rows that follow along a diagonal.

The preferred manner of providing the teeth 21 is by means of dies. 7

As a detail in regard to such dies,the curvature in the die is slightly less than that for the handle 13 to be operated upon so that the roughened portion of the faces 18 Will be confined to a zone 23 that extends over the middle and major portion of the face 18 in each case; that has teeth 21 of the maximum height at and adjacent the middle portion 24; said height diminishing from said middle portion 24 outwardly, and along the border or edge portion 25 of said zone 23 without any pronounced definition there is a dimin ishing to the zero point of elevation for the teeth, or no teeth at all.

In the form shown in Figs. 5 and 6 broken surfaced zones 23* are provided on the opposite faces of the ball-like enlarged end 12" of the handle 13*?i1'1 which the corrugations are provided inthe form of concentric circles. Said corrugations comprise the eleyated ribs 2 1 that are separated by the intervening depressions or valleys QQY, 4

In both of the structures described the handlehas a grip-end of ball form and of oval form of cross-section and zones or spots onthetwoopposite relatively flat faces are roughened to enhance the gripping effect when graspedby'the' hand.

By confining the roughening tozoft'es its described the said rougheriing can be readily effected and by the use of relatively ordinary manufacturing operations, notwithstanding the oval form for the cross-section.

I claim as my invention:

A handle for a screw-driver that terminatesat the grip-end in the form of a ball of oval form and having the end faces and the thicker parts of the side faces of said ball smooth so that the hand may easily be shifted about the handle and the thinner, parts roughened, said iandle being made of a single piece of wood, and said roughened parts of the surface being confined to the two oplbos'it relatively flat faces of the cross-section, whereby the roughening is effected by means of valleys, defining intervening ribs, locdted zones resuectiv ty of said flat faces.

WILLIAM STRATON THOMSON. 

